With the rapid development of electronic products, problems due to electromagnetic interference (EMI) or common-mode noise get more serious to hinder normal operations as the circuitry becomes more complicated.
Conventionally, EMI at low frequencies is eliminated by adopting electromagnetic materials with high inductance. However, such method is not applicable to high-frequency digital circuits and requires large hardware instrumentality.
Recently, a multi-layered electromagnetic noise suppression circuit (for example, the common-mode electromagnetic noise suppression circuit) has been developed using low/high temperature cofired ceramic (LTCC/HTCC) technology to effectively suppress EMI. However, LTCC/HTCC technology is very costly. Such multi-layered electromagnetic noise suppression circuit is only capable of operating at low frequencies, for example, 750 MHz to 1 GHz.
In view of the above, there is a need in providing an electromagnetic noise suppression circuit that can be easily fabricated by adopting a distributed coupling structure for suppressing electromagnetic noise within a wide frequency band.